1. Field of the Invention
The present invention relates generally to a method of encapsulating electronic circuits, and more particularly to a method of encapsulating electronic circuits with an easily removable material.
2. Description of the Prior Art
In many environments it is desirable to encapsulate sophisticated electronic circuitry to prevent it from being damaged by excessive shock or vibration. A good example of such a situation is found in the sophisticated electronic fuse circuit boards carried by modern missiles and artillery shells. Such circuit boards are subjected to intensive accelerating and decelerating shocks as well as substantial in-flight vibrations. Accordingly, it has been the practice in the past to encapsulate these circuits to prevent failure due to the effects of shock and vibration.
In the past epoxies and foamed polyurethanes have been widely used as encapsulants for electronic circuits. When molded around circuit board assemblies and allowed to cure to a rigid state, these materials offer effective protection from the effects of shock and vibration by limiting excessive motion of the boards, components on the boards and electrical connections. However, once a subassembly or complete system is "potted" or encapsulated in a rigid material of the types mentioned, repairs and modifications to the circuit or system become extremely difficult and costly in view of the need to burrow into or remove the encapsulant. Furthermore, circuit assemblies are often damaged when an attempt is made to remove rigid encapsulants for the purpose of servicing or modifying the circuits.
A need therefore exists for an improved encapsulant which is effective in significantly reducing or eliminating the effects of vibration and shock on circuit components, and yet which may be easily removed from circuits or electronic systems to permit them to be serviced, modified, or otherwise processed with ease.